The present invention relates generally to the field of wireless communications, and more specifically to the field of adjusting a phase angle of a recovered data clock signal from a data signal.
In wireless communications, data signals are transmitted over the air in an analog format, typically encoded in such a manner that clocking information for the data is embedded into the data signals and is transmitted along with the data. A typical encoding scheme used is Manchester Encoding where a data transmission clock, operating at twice the frequency of the data signal's clock, is embedded into the data signal. The use of Manchester Encoding inserts a data transmission clock transition into the middle of each data signal period and thus allows the recovery of the transmission clock by processing the received data stream.
One method for recovering the transmission clock in a Manchester Encoded data sequence is to attempt to detect the clock transition in the middle of every data signal bit. This can be problematic due to the fact that depending on a particular bit pattern, each single data signal bit may possess two data transmission clock edge transitions. Also due to noise which is often injected onto the transmitted data signal, the clock transition may not be present in every data signal bit. Additionally, the transmission clock transition may not be sharp enough for the clock edge detection circuitry to detect the transition, or it may be too sharp of a transition and the clock edge detection circuitry cannot detect the transition. Hence clock recovery methods based on the detection of the transition of the clock transition are problematic, depending greatly on the quality of the received signal.
Another digital transmission clock recovery technique includes detecting the presence of a synchronization bit that is used to initial a data signal bit and detecting when the maximum intra-bit signaling distance has been exceeded. This method however, requires the addition of at least one synchronization bit, hence reducing data transmission throughput and increasing circuit complexity.
There is, therefore, a need in the industry for a system addressing these and other related and unrelated problems.